Mechanism for the production of electric arc etching electrodes



MECHANISM FOR THE PRODUCTION OF ELECTRIC ARC E'ICHING ELECTRODES Original Filed June 24, 1942' 3f H11 2 22 263 U t q :2; 32 '7 2-- Patented June 5, 1945 MECHANISM FOR THE PRODUCTION 019 ELECTRIC ARC ETCHING ELECTRODES Theodore Miller, Racine, Wis, assignor to George Gorton Machine (30., Racine, Wis, a corporation of Wisconsin Original application June 24, 1942, Serial No. 448,320, now Patent No. 2,354,871, dated August 1, 1944. Divided and this application June 3, 1944, Serial No. 538,678

6 Claims.

This invention concerns mechanism particularly designed for use in the production of electric arc etching electrodes, specifically, for example, the peculiar very small consumable electrodes that are replaceably employed in the high speed vibratory electrode holders of electric arc etching machines; and the objects and nature of the invention will be apparent to those skilled in the art, in the light of the following description of the accompanying drawing illustrating a preferred example embodiment of my instant invention from among other forms and constructions within the spirit and scope thereof. This application constitutes a division of my parent application filed June 24, 1942, Serial No. 448,320, which issued as Patent No. 2,354,87l on August 1, 1944.

The object of the instant invention is the provision of novel advantageous mechanism to gain accuracy and speed in the production of thedesired electric arc etching electrodes, as well as the desired uniformity of electrodes produced.

A further object, from a specific standpoint, is the provision of mechanism for the accurate and time saving assembly of relatively long lengths of capillary stock tubing with long lengths of tenuous stock electrode wire located therein for the accurate severing of, such stock assemblies into electrode blanks accurately gauged as to lengths of tube and wire and wire projection from each tube, in readiness for finishi g into complete electrodes.

With the foregoing objects in view, and others that may be developed by the following description, my invention consists in certain novel features of structure, organization, combination and sub-combination, as more fully brought out and explained hereinafter and specified by the appended claims.

Referring to'the accompanying drawing, forming part hereof:

Figs. 1, 2, and 3 show the preferred electrode product, greatly enlarged in size, in front elevation, edge elevation, and end view, respectively.

Fig. 4 is a more or less diagrammatical vertical longitudinal section of the mechanism of my instant invention, enlarged in size.

Fig. 5 shows in greatly enlarged side elevation a so-called electrode blank, the product of the mechanism of Fig. 4, ready for completion into the preferred finished electrode, by additional mechanism.

Fig. 6 is an enlarged diagrammatical vertical longitudinal section of mechanism that can be utilized to receive the electrode blank of Fig. 5, and complete the same to form the preferred electrode of Figs. 1, 2, and 3, the compressing plunger being shown in elevated position.

Fig. 7 is an enlarged diagrammatical vertical longitudinal section of the structure of Fig. 6, with its parts in position after the completion of the compressing and shaping operation that produces the preferred completed electrode shown in said mechanism in longitudinal vertical section.

Reference is made to my said parent application Serial No. 448,320, for a full disclosure of the preferred electrode product of my mechanism of the instant application, and of the method preferably followed in the use of the instant mechanism, and of various electric arc etching requirements and peculiarities towhich said preferred electrodes are subjected in use.

The preferred electrode product includes an over long straight length of resilient tenuous consumable electric arc etching electrode wire I, of any suitable high melting metal or alloys of good electrical conductivity, such as tungsten, or tungsten group metal or alloys, or the equivalent thereof for electric arc etching purposes. This wire is usually cylindrical and/or of approximately uniform micro-diameter or cross dimensions throughout its length.

The preferred electrode product also includes a longitudinal relatively short straight tube-like exterior shank 2, composed of capillary tubing of copper or other good electrical conductor metal sufficiently soft when cold to flow laterally when subjected to the necessary shaping compressing force.

The electrode wire extends throughout the length of said tubular shank with straight uncovered short arcing consumable free wire ends 2a. projecting from opposite ends of the shank 'or only from one end thereof. The wire throughout its length within said shank is rigidly gripped by said shank, and, preferably, said free uncovered wire ends have blunt end faces.

To give an idea of the difficulties that would be encountered in handling by the fingers, gauging, and cutting and assembling the capillary tubing of micro-diameter and the resilient tenuous elec trode wire of still smaller diameter, and in producing the very small electrode blanks for final completion to finished form, attention is directed to the fact that where the wire diameter is of the order of .0075 diameter, the capillary tubing therefor is of the order of .012" original interior diameter and .076" exterior diameter; and Where the Wire diameter is of the order of .010, the original interior diameter of the tubing therefore is of the order of .020" diameter; and where the wire diameter is of the order of .015", the tubing therefor is of the order of .025" original internal diameter, although I do not wishto so limit my instant mechanism invention.

In the completed preferred electrode products, the length of the shank 2 is of the order of elevensixteenths of an inch, more or less, and the projecting uncovered wire ends 2a, usually alike in length, of the order of six sixty-fourths to twelve sixty-fourths of an inch, more or less.

In the particular preferred electrode product, illustrated as an example, the shank 2 is throughout the length of its rear side 2b, partially cylindrical in cross section to form a longitudinal surface on which the electrode is slidable. This partially cylindrical surface 2b is approximately concentric with the wire and extends there around through approximately 180, more or less.

The opposite or front longitudinal side of the example electrode product is flat providing longitudinal opposite end flats 2c, and the intermediate cross groove 2d, the floor of which provides a depressed fiat and the opposite sides of which provide parallel stop walls 26, while the opposite ends of said cross groove 2d provide opposite laterally projecting lips or bulges 2f, that not only stiffen the electrode shank but also forms stops for the purposes described in my said parent ap lication.

To reduce to the minimum finger manipulation, handling, gauging, and severing of the microparts, I have discovered that the object sought is facilitated by first producing a so-called electrode blank, for example, the blank A, B, Fig. 5, that consists of a straight length of the soft metal tube A, of the length of the shank 2, of the finished electrode, containing throughout its length in slidable longitudinal relation, the electrode wire B, of the length required for the finished electrode with its longitudinally projecting free uncovered consumable end or ends 2a.

My instant invention consists of mechanism for use in the convenient rapid production of the desired accurately assembled, gauged and separated electrode blank, with the minimum use of the fingers, which blank can then be readily passed on to suitable means for finishing such blank into the finally completed electric arc etching electrode.

By Fig. 4 of the drawing I have, more or less, diagrammatically illustrated a preferred example embodiment of my said instant invention.

This example embodiment comprises a substantially horizontal elongated body frame or base block 6, at its front end provided with a rigid upstanding plate or post 5b, pierced by a preferably circular horizontal transverse guiding and centering tapered eye 5, for slidably receiving an elongated straight stock length of the required soft metal capillary cylindrical tubing A, of the required internal and external diameters, and to maintain said stock length against lateral deflection and to permit longitudinal straight line movement through the eye 5, and transversely across the stock tube guiding and sustaining top end of upright wall 'l,rigid with base 6, and spaced a normally fixed gauged distance from the rear side of post 5b, to provide an open-top well 5a, across which said stock length A extends, establishing a fixed transverse vertical stock length severing plan'e 5a, in which suitable stocklength cutting off or severing means is confined to operate. This vertical severing plane establishes the stock length severing station, preferably located midway between the vertical rear side of post 5b, and the vertical front side of wall I.

At a predetermined distance longitudinally of the base 6, to the rear of said severing station or plane, is located a normally-fixed stock length stop 8a, formed by the front vertical side of wall 8, rising from base 6. The length of this distance from said severing plane to said stop 8a is equal to the desired predetermined tube length A, of the electrode blank A, B, and of the finished electrode shank 2.

A stock length of electrode wire B is threaded longitudinally and slidably through the straight tube stock length A, in the mechanism of Fig. 4, and transversely across the top surface of wall 8, until stopped by the engagement of the rear end of said wire length with the wire-stop vertical front surface Hla, of a longitudinally adjustable horizontal screw ll], longitudinally alined with the common longitudinal axis of the tube and wire stock lengths A, B, located in the mechanism of Fig. l, The screw in is threaded in and longitudinally adjustable through a transverse tapped hole extending through the normally fixed wall 9, upstanding from base 6. The distance longitudinally of the base 6, from the vertical stop face 811, for the tube stock length to the vertical stop surface Illa, for the wire stock length, is set to predetermine the wire length necessary for the opposite uncovered consumable wire lengths 2a, of the finished electrode.

In the use of the mechanism of my instant invention for the production of the electrode blanks A, B, of Fig. 5, I select a long straight stock section of the copper tubing of a length to produce a predetermined number, usually, a multiplicity of tube sections each of the required length of the tube A, of Fig. 5, that is, of the required length of the shank 2, of each finished electrode to be produced. This very long stock tube length is then longitudinally slipped through eye 5, and transversely across the severing plane or station, and transversely across sustaining and guiding wall I, with its flat front end abutting stock tube stop 8a.

Before the long length of stock tubing is inserted in the mechanism of Fig. 4, usually an over long stock length of the tenuous resilient electrode wire is threaded through the bore of the stock length of tubing. The stock wire is equal in length to the length of the stock tubing plus the aggregate lengths of the free wire ends 2a, needed for the aggregate number of shank lengths to be cut from said stock tubing length.

The stock lengths of tenuous electrode wire are unwound from coils or reels and hence are usually under constant tension to depart from a straight line and assume an arcuate shape. This tension tends to frictionally hold the wire lengths inserted in the soft metal capillary tubing against excessive looseness and too-easy sliding therein, by reason of the'lateral pressure and engagement of various portions of the wire with the interior surfaces of the tubing, while leaving the wire free to longitudinally slide through the tube under moderate pressure. If the wire is too straight to exert the required light pressure against the interior wall of the tube, a simple curling operation will impart the necessary arcuate form to the wire. This light frictional contact between wire and tube prevents the wire from falling from the tube by action or gravity or other forces imposed upon the tube and wire during fabrication prior to clinching.

When the stock length of tube has been forced forwardly in the mechanism of Fig. 4, the stock length of wire B is forced thnoughthe stock tubing until the wire end engages wirestop Illa,-

which thus provides the projecting wire length from tube stock 8a, to wire stop Illa, equal to the two uncovered wire ends 2a, required for a double end or reversiblefinished electrode.

Thus by transversely severing the stock tube length and its contained stock wire length at the severing station or plane 5a, the electrode blank A, B, of Fig. 5, is produced, and can be'passed from the instant mechanism to other means for producing the finished product.

After each such severing operation, the stock tubing length is pushed forward against stop 8a. and the stock length of wire therein is pushed forward against wire stop Illa, and the severing operation is carried out. These operations can be rapidly carried out until the stock lengths of tubing and wire needrepl'enishment.

Any suitable severing means can be employed, although from a specific standpoint, I prefer to employing frictional grinding or abrasive severing means where tungsten wire or wire of the tungsten nature or characteristics, is employed, which cannot be satisfactorily cut, for electric arc etching purposes, by shearing or shipping.

As an example, I diagrammatically illustrate a suitably driven rotary abrasive saw, grinding wheel or thin rotary abrasive or grinding disk I I, operating in said severing plane and carried by any movable support or hanger, normally holding said abrasive severing disk II, above and remote from the stock tubing and wire to be severed, but capable by manual operation to be forced down or vertically to quickly perform each severing operation, and then return to normal inoperative position. The severing disk might be fixedly located, and the mechanism of Fig. 4 movably located for shifting to and from severing relation to said rotary severing disk, It will be noted that the instant mechanism produces the electrode blank with square cut substantially blunt tube and wire ends, which are satisfactory from a specific standpoint, but I do not wish to so limit all features of my instant invention.

Suitable means are provided to receive the electrode blank A, B, of Fig. 5, and complete the same to the desired finished electric arc etching form and condition.

For example without desiring to so limit my instant invention, in Figs. 6 and 7, I more or less diagrammatically illustrate mechanism that can be employed for this finishing operation, referring to my said parent application, Serial No. 448,320, for detail illustration and explanations.

This example finishing mechanism comprises a fixed female die I2, the top surface of which provides a more or less flat die face, that throughout its longitudinal length provides an approximately central straight open-top die groove I3, cylindrical in cross section through, say, slightly less than 180 and preferably of uniform radius throughout its length, with the width of itsopen top slightly less than the diameter of the cylinder.

The die groove I3, to receive the electrode blank A, B, is at least equal to the length of the electrode shanks to be finished therein, but usually is longer, and open at its rear end and also at its front end, that ispartially closed by a normally fixedly located transverse wall forming a tube stop I4.

A horizontal screw I5, axially alined longitudinally with the longitudinal axis of groove I3, is carried by and longitudinally adjustable through a. normally-fixedly located post I6a, upstanding from the front end of die I2, and spaced forwardly from tube stop I4, and the front end of die groove I3. The rear end face of this screw I5, provides wire stop face [5a, longitudinally spaced a predetermined distance from thevertical plane of the'tube stop face I4, that determines the equal lengths of the two consumable wire ends that are to project longitudinally from the finished electrode.

Each electrode blank A, B, includes a cylindrical stock tube length A, of the length of the shank 2, of the desired finished electrode, with a stock wire B, extending throughout the full length thereof and frictionally held therein with a length projecting from one end thereof equal to twice the lengths of the free ends 2a, that are to project from the desired reversible finished electrode. This electrode blank A, B, is then longitudinally slipped, projecting wire end rearmost into the outer end of the die groove I3, until the advancing tube end is stopped by engagement with tube stop I4, thereupon the wire length is pushed forward through the tube until stopped by engagement with wire stop face I5a, whereupon equal length wire ends project from the opposite ends of the tube length surrounding the central portion of the wire length.

Thereupon the operation of compressing, swaging and shaping the tube length to the required completed electrode form can be carried out, and the finished article can then be readily lifted from the die groove.

A reciprocatory power or manually driven swaging and compressing male die head I6 complementary to the die It, with its die groove I3, is usually employed in this particular example, having male die portions Ila, Ila, I lb, to compress, swage and shape the tube, in cooperation with die I2, and form the fiats and lips of the front face and the longitudinally rounded back surface of the finished electrode.

What I claim is:

1. Mechanism for use in the production of an electric arc etching electrode having a relatively short tubular shank containing and rigidly gripping a relatively long electrode wire length extending longitudinally therethrough and projecting longitudinally therefrom; said mechanism providing a straight line guideway adapted to receive in longitudinally slidable relation a straight length of tube having an over long length of tenuous electrode wire extending therethrough and projecting longitudinally therefrom; a tube length halting stop located in the path of said advancing tube length and out of the path of said wire length; and a wire length halting stop settable longitudinally of said guideway at a predetermined longitudinal gauging distance along said guideway from said tube length stop,

2. Mechanism for use in the production of electric arc etching electrodes; said mechanism providing a straight-line guideway for the longitudetermined distance in advance of said stock tube halting stop.

3. Mechanism for use in the production of electric arc etching electrodes, providing a straight line guideway for an advancing elongated stock length of tubing containing a relatively longitudinally slidably elongated stock length of tenuous electrode wire, a gauging stock tube length stop along said guideway, a gauging stock wire length stop along said guideway located a predetermined distance in advance of said tube length stop, and a stop tube length and stock wire length severing station located along said guideway a gauging predetermined distance from said tube length stop.

4. Mechanism for use in the production of electric arc etching electrodes, ofthe type substantially as described; said mechanism comprising a base providing a fixed straight line guideway adapted to receive in longitudinal sliding and guiding relation a length of straight tube through which an overlong length of tenuous wire extends and from which it projects longitudinally; a tube halting stop normally-fixedly located in the path of the advancing tube and out of the path of the wire; and a wire halting stop located a predetermined gauging longitudinal distance from said tube halting stop and comprising a longitudinally adjustable screw axially alined with said guideway and providing a transverse wire engaging end face. 7

5. Mechanism for use in the production of electrode blanks, substantially a described, for finishing into completed electric arc etching electrodes, said mechanism providing a straight-line guideway adapted to receive in longitudinal guiding and advancing sliding relation, an elongated stock length of tubing through which an over long stock length of tenuous wire extends in relative longitudinal sliding relation; means providing a severing station across said guideway in a plane perpendicular to the longitudinal axis of the tube and wire stock lengths, said means including a frictional abrasive tube and wire severing device; a stock tube length halting stop spaced along said guideway a predetermined longitudinal distance from the plane of said severing station; and a stock Wire length halting stop a predetermined distance in advance of said tube length stop.

6. Mechanism for use in the production of electrode blanks for finishing into completed electric arc etching electrodes of the type substantially as described, said mechanism including a base providing a longitudinal normally-fixedly located guideway for an elongated stock length of tube having a stock length of tenuous electrode wire extending therethrough in relative longitudinal sliding relation, for cutting into electrode blanks each having a tube and an overlong wire both of electrode length, said guideway including a normally fixed eye; means es tablishing a transverse tube and wire severing station; normally fixed tube stop located a predetermined distance in advance of said station; and a screw longitudinally alined with said eye and guideway and longitudinally settable to form a wire stock length stop a redetermined dis-' tance in advance of said tube length stop.

THEODORE MILLER. 

